Online advertising uses the Internet to deliver promotional marketing messages to consumers. Also known as Internet advertising, it includes email marketing, search engine marketing, social media marketing, various types of display advertising (including web banner advertising), and mobile device advertising. Like other advertising media, online advertising frequently involves both a publisher, who integrates advertisements into its online content, and an advertiser, who provides the advertisements to be displayed on the publisher's content. Other potential participants include advertising agencies who help generate and place the ad copy, an ad server who technologically delivers the ad and tracks statistics, and advertising affiliates who do independent promotional work for the advertiser. Online advertising is growing rapidly and is widely used across virtually all industry sectors.